1. Field of the Invention
The present invention relates generally to a cordless window covering, and more particularly to an apparatus for raising and lowering a covering member of a window covering.
2. Description of the Related Art
In a conventional cordless window covering, it has a headrail, a bottom rail, a covering member with opposite end connected to the headrail and the bottom rail, and a driving device for raising and lowering the covering member. Typically, the driving device is received in the headrail. The conventional driving device is provided with a reel member. The reel member provides a recovering force to sustain the weight of the covering member and the bottom rail, so that when a user lowers the covering member, the bottom rail will stay at a position where the user releases the covering member. On the contrary, when a user raises the covering member, the recovering force of the reel member will wind the covering member. The conventional reel member has a spiral mainspring to provide the recovering force. The mainspring will fatigue after a long time of use, which makes the covering member unable to be totally received in the headrail.